Method of and apparatus for vial transferring and changing

ABSTRACT

An automatic changing apparatus for sample vials and like regularized objects is provided, wherein a rectilinear array of vials is indexed along an X-axis, rows of the array are indexed seriatim along a Z-axis, and individual vials of the Z-axis indexed rows are indexed seriatim past a counting station along a Y-axis. Photoelectric sensors are provided to override portions of the indexing mechanism if no sample vials are present in array rows or individual compartments.

United States Patent Frank et al.

[ Dec. 16, 1975 METHOD OF AND APPARATUS FOR VIAL TRANSFERRING ANDCHANGING Inventors: Edmund Frank, Chicago; Edward F.

Polic, Lisle, both of I11.

Packard Instrument Company, Inc., Downers Grove, 111.

Filed: Apr. 10, 1970 Appl. No.: 27,406

Assignee:

US. Cl. 214/310; 250/106 SC Int. C1. B65G 65/04 Field of Search 198/32;250/106 SC;

References Cited UNITED STATES PATENTS 8/1954 Hirsch et a1. 198/246/1962 Kern 214/l6.4

Flynn 214/310 Frank et al. .l 214/164 Primary ExaminerRobert J. SparAssistant Examiner-Lawrence J. Oresky Attorney, Agent, or FirmWolfe,Hubbard, Leydig, Voit & Osann, Ltd.

[5 7] ABSTRACT An automatic changing apparatus for sample vials and likeregularized objects is provided, wherein a rectilinear array of vials isindexed along an X-axis, rows of the array are indexed seriatim along aZ-axis, and individual vials of the Z-axis indexed rows are indexedseriatim past a counting station along a Y-axis. Photoelectric sensorsare provided to override portions of the indexing mechanism if no samplevials are present in array rows or individual compartments.

14 Claims, 21 Drawing Figures US. Patent Dec. 16, 1975 Sheet 1of93,926,323

US. Patent Dec. 16, 1975 Sheet 3 of9 3,926,323

US. Patent Dec. 16, 1975 Sheet40f9 3,926,323

US. Patent Dec. 16,1975 Sheet50f9 3,926,323

US. Patent Dec. 16, 1975 Sheet 7 of9 3,926,323

US. Patent Dec. 16, 1975 Sheet8of9 3,926,323

US. Patent Dec. 16, 1975 Sheet9of9 3,926,323

Z M MM 1 METHOD OF AND APPARATUS FOR VIAL TRANSFERRING AND CHANGINGRELATED APPLICATIONS This case is related to application Ser. No. 27,411filed by Frank (sole) as follows: Frank et al. (Ser. No. 27,406) madethe generic invention which Frank (sole, Ser. No. 27,411) perfected. Theperfected Frank embodiment is disclosed as the best mode and only modein both applications (27,406 and 27,411). Frank et al. (Ser. No. 27,406)who had the generic concept, have included generic claims in theirapplication, while Frank (Ser. No. 27,41 1) has claims only to theembodiment that he invented.

DESCRIPTION OF THE INVENTION This invention relates generally tochanging and transfer methods and mechanisms for sample vials and thelike and, more particularly, concerns methods and mechanisms forunloading sample vials and like objects from trays or other regularizedcontainers and for transporting the sample vials to and from a countingor other operation station.

BACKGROUND OF THE INVENTION Liquid scintillation spectrometers, orapparatus designed to provide spectral analysis of test samplescontaining one or more radioactive isotopes disposed in a liquidscintillator contained in a sample vial, have been successfully employedin medical research and allied laboratories for several years. In suchapparatus, trays holding an array of sample vials which contain thescintillator and isotope are loaded into the apparatus, and the vialsare thereafter manipulated seriatim into and out of a detectormechanism. To this end, annular trays such as that disclosed in US. Pat.No. 3,257,561 to Packard et. al. have heretofore been provided, togetherwith the sample vial transfer mechanisms therein disclosed. The wideacceptance of this type of scintillation spectrometer and its associatedvial-handling mechanism has led to the development of still other typesof vialhandling and changing apparatus capable of accommodating a largenumber of sample vials.

It is, therefore, the general object of this invention to provide samplechanging methods and apparatus wherein large numbers of sample vials orlike objects may be handled and manipulated with ease and rapidity.

Another important object of the invention is the provision of a samplechanging apparatus wherein compact arrays of sample vials may be easilyand quickly inserted into and removed from the sample changingapparatus. More specifically, it is an object to provide a samplechanging apparatus wherein the arrays of the sample vials may beinserted into and removed from the apparatus without halting theoperation of the apparatus.

It is yet another object to provide a sample changing apparatus whichwill quickly and efficiently manipulate the sample vials withoutengaging in useless motion when an empty container compartment isencountered by the apparatus.

It is yet another object to provide a sample changing apparatus which isrelatively simple in design, and yet rugged and reliable in operation.

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings, in which:

FIG. 1 is a top plan view showing the overall arrangement of the samplechanging apparatus and the associated detecting and counting mechanism;

FIG. 2 is a fragmentary front elevational view of an exemplaryapparatus, here depicting several samplecontaining tray arrays;

FIG. 3 is an end elevational view of the exemplary sample changingapparatus shown in FIGS. 1 and 2;

FIG. 4 is an enlarged perspective view, partially exploded, showing anexemplary tray-supporting carriage used in the apparatus;

FIG. 5 is a perspective view in partial section showing a typical sampletray used in connection with the sample changing apparatus disclosed;

FIG. 6 is an enlarged sectional view taken substantially along the line66 of FIG. 2 showing in detail an exemplary rear support and carriagedrive mechanism used in the illustrated apparatus;

FIG. 7 is an enlarged sectional view taken substantially along the line77 in FIG. 4 showing in detail the from support of the illustratedapparatus;

FIG. 8 is an enlarged sectional view taken substantially along the line88 of FIG. 2 showing in greater detail the sample vial-elevating comband its associated driving apparatus;

FIG. 9 is an enlarged sectional view taken substantially along the line99 in FIG. 8 illustrating in detail apparatus for guiding the motion ofthe sample vialelevating comb;

FIG. 10 is an enlarged sectional view taken substantially along the line1010 in FIG. 8 illustrating in detail the lower comb guide;

FIG. 11 is an enlarged sectional view taken substantially along the line11-11 in FIG. 8 showing in detail the mechanism by which the samplevial-elevating and lowering comb is manipulated;

FIG. 12 is an enlarged sectional view taken substantially along the line1212 in FIG. 8 showing in detail the X-conveyor alinement switch andassociated apparatus;

FIG. 13 is an enlarged sectional view taken substantially along the line13-13 in FIG. 11, showing a typical embodiment of the comb elevatingdrive, with the comb illustrated in its upwardmost position;

FIG. 14 is an enlarged partial top plan view, showing in further detailthe Y-axis conveyor;

FIG. 15 is a partial side elevational view of the Y conveyor, showing infurther detail a number of the parts associated therewith;

FIG. 16 is an enlarged perspective view showing in further detail thesample vial positioning or pilot mechanism used in association with theelevator mechanism of the detector mechanism;

FIG. 17 is a perspective view showing further the details of the Y-axiscarriage;

FIG. 18 is an enlarged sectional view taken substantially along the line18-48 of FIG. 14, and showing yet further details of the Y-axiscarriage;

FIG. 19 is an enlarged sectional view taken substantially along the linel919 in FIG. 14, and showing yet other details of the Y-axis carriagemechanism;

FIG. 20 is a partial elevational view showing in further detail portionsof the carriage movement control mechanism; and,

FIG. 21 is a perspective view showing in somewhat stylized or schematicform certain of the electrical wiring and connections used in thepresent embodiment of the invention.

While the invention will be described in connection with a preferredembodiment, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications, and equivalents as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

Turning first to FIG. 1, there is shown a liquid scintillation apparatuscabinet 31 housing a scintillation detector mechanism 32. A top opening33 is provided in the scintillation detector mechanism 32 for theinsertion of sample vials 35 into the sample detector mechanism 32.Rectangular arrays of the sample vials 35 spaced in columns and rowsalong respective X and Y Cartesian coordinates of the arrays arenormally carried in trays 36 (see FIG. In the practice of the presentinvention, such trays are preferably constructed in the manner describedin greater detail in the aforesaid copending Frank application, Ser. No.27,405, assigned to the assignee of the present invention. In turn,arrays of the trays 36 may be loaded onto the sample changing apparatusand manipulated as hereinafter described. In the illustrated embodimentof the invention, it is contemplated that the sample vials 35 will carrya radioactive isotope-containing substance dissolved, suspended, orotherwise mixed in a liquid scintillation medium comprising a solventand one or more of numerous commercially available scintillators orfluorescent materials, the sample vial having light-transmissive walls.Scintillations or light flashes may then be counted by means ofappropriate photomultipliers and other apparatus carried within theliquid scintillation detector mechanism, at a counting station providedfor that purpose.

In accordance with the invention and for alining successive Y-axis rowsof the sample vial array with a transfer station 38, first indexingapparatus is provided including a carriage 40 (best illustrated in FIG.4), upon which the trays 36 may be manually placed, and which supportsand moves the trays 36 along the X- axis. For supporting the carriage 40and for allowing motion of the carriage 40 along the X-axis in theillustrated embodiment, guide brackets 41 having front support rollers42 mounted thereupon are secured, by any convenient means, to the bottomfront of the carriage 40, as best seen in FIG. 7. For supporting therear of the carriage 40, rollers 43 are provided which engage a track 44mounted upon the vertical rear wall 45 of the apparatus.

The carriage 40 may be driven in either direction along the X-axis by acarriage drive mechanism. As best seen in FIG. 2, an endless belt 47 ispassed around an idler 48 and a drive pulley 49. The pulley 49 isrotated by a small servomotor 49:! mounted on the vertical rear wall 45of the apparatus. As best seen in FIG. 6, a top portion 50 of the belt47 is secured to a belt connecting bracket 51, which bracket is, inturn, connected to a carriage positioning switch 52. When the belt 47 isdriven by the servomotor 49a, the belt connecting bracket 51 andposition switch 52 are moved in a direction parallel to the X-axis, andthe carriage 40, which is secured to the carriage position switch 52, ismoved in unison therewith.

Precise alinement of the carriage 40 with the transfer station 38 isaccomplished by means of an X-axis positioning mechanism 54, best seenin FIGS. 12 and 13. In the embodiment illustrated, a small contactroller 55 is pivotally mounted on a roller plate 56, the plate itselfbeing pivoted about a fixed bearing 57. The plate 56 and roller 55 areurged into light contact with the carriage position witch 52. As will bemore fully explained below, a strike lever 60 may be caused to contactthe roller plate 56, and to urge the plate 56 and roller 55 to theright, as shown in FIG. 12, thus forcing the roller 55 to center withinone of the notches 61 provided in the carriage position switch 52. Suchaction of the roller 55 removes and slight misalinement of the carriageswitch 52 and attached carriage 40 with the transfer station 38. Thus,the position of any given row of containers 35 may be accurately alinedwith the transfer station 38.

Indexing apparatus is also included, in accordance with another aspectof the invention, for indexing a row of containers along the Z-axisbetween the transfer station 38 and additional transfer means. In theillustrated embodiments, and as best seen in FIGS. 8 through 15, thisindexing apparatus includes an elevating comb structure 65 having aplurality of teeth 66, which teeth 66 are adapted for insertion into andout of holes 67 and 68 formed for that purpose in the bottom of thecarriage 40 and sample vial-containing trays 36, respectively. By movingthe comb 65 upwardly when a row of sample vials 35 is alined with thetransfer station 38, the vials 35 may be ejected upwardly from the tray36. In the illustrated embodiment, the comb 65 is elevated by means of aZ-drive motor 75, the output shaft 69 of which is constructed to anddrives a cam arm 70, the latter being connected to the slide 71 of ascotch gear arrangement 72. As the motor 75 rotates the cam arm 70, theslide 71 moves between two horizontally disposed slide rails 73 and 74.

Pursuant to the invention, the cam arm 70 is formed with an extension 76having a cam surface 77 thereupon. A cam follower 78 is mounted upon thestrike lever 60 described above. As seen in FIG. 13, rotation of the camarm 70 simultaneously pivots the strike lever 60 by the action of thecam surface 77 and cam follower 78 which is mounted on the strike lever60. As described above, the strike lever is positioned for engagementwith the pivot plate 56 which carries the carriage positioning roller55. Thus, as the comb teeth 66 are elevated through the carriage holes67 and tray holes 68 to eject the vials 35 from the tray 36, the camsurface 77 and follower 78 cause the strike lever 60 to force the roller55 into positioning engagement with the carriage position switch 52. Arow of vials 35 is resultantly positioned accurately at the transferstation 38 immediately prior to the rejection of the vials 35 from thetray 36 by the comb tines 66.

In the illustrated embodiment of the device, the Z- axis, or vertical,motion of the comb 65, is guided by comb-mounted rollers 80 whichoperate in Z-axis oriented tracks 81 and 82, conveniently mounted on theapparatus structure, and by rollers 83 mounted between the tines 66 asbest seen in FIGS. 9, l0 and 13.

In further accordance with the invention, indexing apparatus is providedfor indexing a row of containers along the Y-axis so that the containersmove past a loading station 99 in seriatim order for alining thecontainers with the station. In the present embodiment, a Y-axiscarriage 86 is disposed generally above the elevating comb 65 for motionalong the Y-axis. As can be best seen in FIGS. 14-20, the carriageincludes a partitioned mobile conveyor 87 which contains a plurality ofbottomless compartments 88 for receiving the Z-axis indexed vials 35.Skirts 89, 90 (FIG. 18) are provided for guiding the upwardly thrustvials 35 into the appropriate compartments 88.

When the vials 35 are introduced into the compartments 88, the conveyor87 is moved along the Y'-axis by an endless belt 91 driven by a Y-axisdrive motor 92. The belt, as illustrated (FIG. 17), is secured to theconveyor 87 by a belt clamp 93. As best seen in FIGS. 11 and 18, theconveyor rides upon grooved rollers 94 which engage a correspondingtrack 95 on one side, and further ride upon smooth-surfaced rollers 96which engage a C-shaped channel track 97 on the other side.

Y-axis indexing motion of the conveyor 87 is thus caused by activationof the Y-axis motor 92 (FIG. 14). When set in motion, the conveyor 87drags the vials 35 which have been inserted into the compartments 88across the tips of the comb tines 66 and, one after another, past aloading station 99 (FIGS. 1, 14 and 19). A vial-supporting track 100 isprovided for those portions of the Y-axis not occupied by tines 66 orthe comb 65. To assist in positioning the compartments 88 over theloading station 99, notches 101 are formed in one skirt 90 forengagement by a positioning roller 102. This roller 102, as best seen inFIGS. 19 and 20, is mounted on a pivotable ann 103 which is biased, asby a spring 104, into one of the notches 101. The conveyor 87 is urgedinto an accurately located position over the' loading station 99 bymotion of this roller.

When a vial 35 is positioned at the loading station, as bestillustrated'in FIGS. 3, 16, 19 and it rests upon an elevator 106 whichis operated by mechanisms (not shown) located inside theliquidscintillator detector mechanism 32. The elevator may be loweredinto the detector mechanism 32, drawing with it the vial35, andpositioning the latter in a counting station (not shown). Guides 107,108 are provided for centering the vial 35 on the elevator 106 duringits downward and upward motion; the guides 107, 108 and track 100 aretapered at their respective ends to assist in this guidance.

Once the via] 35 is drawn into the detector mechanism, thescintillations or light flashes occurring therein may be counted, asgenerally known in the art, over measured time or until a present countis reached. Thereafter, the sample vial is again thrust up into its Y-axis carriage compartment 88 by the elevator 106, and the Y-axis drivemotor is actuated to draw a succeeding vial over the elevator.

Embodiments of the switches and circuitry used to operate the mechanismin accordance with the invention are illustrated in FIG. 21 andelsewhere. When the indexing mechanism is activated by the operator, theX-axis drive motor 49a is activated, and draws the vialsupportingcarriage 40 along the X-axis as described above. A limit switch 150actuated by a switch finger 151 halts the X-drive motor 49a and X-axismotion of the carriage when the first row of vial compartments arepositioned at the transfer station 38.

The activation of switch 150 also activates the Z-axis motor 75, raisingthe comb 65 and thrusting the vials located in the transfer stationupward along the Z-axis, until detent 152 located appropriately upon thecomb 65 engages switch 153, thereby halting the Z-axis drive motor 75and the upward motion of the comb 65. Switch 153 additionally activatesthe Yaxis drive motor 92 to move the indexing vials along the Y-axis asabove described.

When biased roller 102 engages the first notch 101 on the skirt 90, thepivotable arm 103 upon which the roller 102 is mounted activates switch154 halting the Y-axis motor and motion. Mechanism (not shown) withinthe detector mechanism 32 then lowers and later raises the sample vialupon the elevator. Completion of the upward motion of the elevatorserves to reactivate the Y-axis drive motor by appropriate circuitry(not shown), thus indexing the next vial compartment over the countingstation, whereupon the roller 102, arm

103, and switch 154 again halt Y-axis motion.

When all Y-axis carriage compartments have been indexed past the loadingstation, switch 155 is engaged by the Y-axis carriage, the Y-axis motoris reversely driven and, when the carriage 40 is in its originallocation over the comb 65, the Y-axis motion is halted by switch 156.Switch 156 also actuates the Z-axis drive motor 75, which lowers thecomb 65 and vials located thereupon until a detent 157 engages switch153, whereupon the Z-axis motion is halted and the X-axis drive motor49a is reactivated to bring the next row of sample vials to the transferstation 38. By appropriate circuitry, this operational cycle iscontinued until the X-axis carriage engages switch 158, whereupon the X-axismotor 49a is reversely and continuously driven until the X-axiscarriage is returned to its original position, the reverse motion beinghalted by switch 159.

In accordance with yet another aspect of the invention, the apparatus isfurther designed to manipulate the sample vials without engaging inuseless motion where an empty compartment is encountered. To this end,several optical switches are provided, the switches comprising a lightsource and a photo-sensitive cell. When an opaque object, such as thecap upon a sample vial, interrupts the light beam falling upon the cell,the cell-associated switch devices are actuated.

As illustrated here, an optical switch 160 and associated light source161 are positioned so as to sense, by the interruption of the lightbeam, the presence or absence of sample vials in any row of containerslocated at the transfer station 38. If no sample vial is sensed in therow, appropriate circuitry causes the X-axis motor 49a to continue theindexing motion without the activation of the Z-axis motor 75 or theY-axis motor 92. Similarly, the optical switch 163 and associated lightsource 164, together with appropriate circuitry, cause continued Y-axisindexing of the Y-axis carriage if no sample vial is sensed within aY-axis carriage compartment as the compartment passes the loadingstation 99.

Means are further provided for indicating to a control station (notshown), the designation for a sample vial located at the countingstation. For this purpose, an X-axis position readout switch 165 isincluded for sensing and indicating the sample vial row which is locatedat the transfer station 38 for indexing along the Y-axis. Similarly, aY-axis position readout switch 166 is included for sensing andindicating the Y-axis carriage compartment which is located at theloading station 99. By means of such switches, identification can beautomatically made of the source of the scintillations being countedwithin the detector mechanism.

I claim as my invention:

1. A method of indexing sample vials to a predetermined point from arectangular array of vials disposed in columns and rows along respectiveX and Y cartesian coordinates, comprising the steps of:

A. indexing the entire array along the X-axis to position one of therows of vials at a transfer station disposed on a Y-axis coordinatealigned with said point;

B. indexing each row of vials along a Z-axis to shift said row out ofthe plane of said array;

C. incrementally indexing each row of vials received in said transferstation from said station along the Y-axis coordinate aligned with saidpoint to successively position, in seriatim order, each vial in said rowat said point; and thereafter D. again indexing the entire array alongthe X-axis to position successive rows of the vials in said array in thetransfer station in seriatim order after all of the vials in thepreceding row have been indexed along the Y-axis to said point.

2. The method according to claim 1 further characterized by scanningeach Y-axis coordinate of said array to determine whether each saidcoordinate contains at least one vial and automatically indexing theentire array along the X-axis past any Y-axis coordinate devoid of atleast one vial to the next Y-axis coordinate containing at least onevial.

3. The method according to claim 1 further characterized by scanningeach X-axis coordinate of the row of vials being indexed along theY-axis to determine the presence or absence of a vial at each suchX-axis coordinate and automatically indexing any X-axis coordinate insaid row devoid of a vial past said point along said Y-axis coordinate.

4. The method according to claim 1 further characterized in that eachvial positioned at said point is transferred from said point to acounting station and back to said point before the next succeeding vialis indexed to said point.-

5. The method according to claim 4 further characterized in that thevial is transferred between said point and said counting station along aZ-axis.

6. A test sample changing apparatus for use with at least onerectangular array of sample vials disposed in columns and rows alongrespective X and Y cartesian coordinates of said array and fortransferring all of said vials one at a time to a predetermined point,said apparatus comprising, an apparatus frame, means on said framedefining said point, a transfer station on said frame spaced from saidpoint along a Y-axis coordinate, and means for holding at least onerectangular array of vials on said frame at a location spaced from saidstation, characterized in that first indexing means are provided forincrementally indexing an entire one of said arrays along the X-axis forsequentially aligning each Y-oriented row of vials with said station,second indexing means are provided for shifting each row of vialsaligned with said transfer station along a Z-axis tr shift said row ofvials out of the plane of said array third indexing means are providedfor incrementally indexing each row of vials aligned with said statioralong said Y-axis coordinate to sequentially positior each vialcontained in each said row at said predetermined point in seriatimorder.

7. Apparatus as set forth in claim 6 further charac terized in that saidsecond indexing means is rendered operative after said first indexingmeans and prior to said third indexing means.

-8. Apparatus as-set forth in claim 6 further characterized in that saidfirst, second and third indexing means are repetitively cycled in thefollowing order:

a. said firstmeans;

b. said second means;

c. said third means;

d.. said third means, reversely driven; and

e. said second means, reversely driven; until all of said vials in saidrectangular array have been transferred from said array to said pointand back to said array.

9. Apparatus as set forth in claim 6 further characterized in thatsensing means are provided for determining the presence of at least onevial in each Y-oriented row of said array and for causing said firstindexing means to automatically index said array through multipleincrements so that Yoriented rows devoid of vials are indexed pastsaid,station.

10. Apparatus as set forth in claim 6 further characterized in thatsensing means are provided for determining-thepresence or absence of avial at each X- coordinate in the row of vials being indexed from saidstation to said point and for causing said third indexing means toautomatically index said row through multiple incrementsso that eachX-coordinate in said row devoid of a vial is indexed past said point.

1 1. Apparatus as set forth in claim 6 characterized in that means areprovided for transferring each vial positioned at said point from saidpoint to a sample proce ssing station and back to said point.

12. Apparatus as set forth in claim 1 1 further characterizedin thatsaid processing station comprises a lighttight chamber and means areprovided for counting light scintillations occurring in each said samplevial while the latter is positioned in said chamber.

13. Apparatus as set forth in claim 1 1 further characterized in thatsaid point and said processing station are spaced apart on a Z-orientedaxis.

14. Apparatus set forth in claim 6 further characterized in that saidthird indexing means is operative only while said row of vials is out ofthe plane of said array.

1. A method of indexing sample vials to a predetermined point from arectangular array of vials disposed in columns and rows along respectiveX and Y cartesian coordinates, comprising the steps of: A. indexing theentire array along the X-axis to position one of the rows of vials at atransfer station disposed on a Y-axis coordinate aligned with saidpoint; B. indexing each row of vials along a Z-axis to shift said rowout of the plane of said array; C. incrementally indexing each row ofvials received in said transfer station from said station along theY-axis coordinate aligned with said point to successively position, inseriatim order, each vial in said row at said point; and thereafter D.again indexing the entire array along the X-axis to position successiverows of the vials in said array in the transfer station in seriatimorder after all of the vials in the preceding row have been indexedalong the Y-axis to said point.
 2. The method according to claim 1further characterized by scanning each Y-axis coordinate of said arrayto determine whether each said coordinate contains at least one vial andautomatically indexing the entire array along the X-axis past any Y-axiscoordinate devoid of at least one vial to the next Y-axis coordinatecontaining at least one vial.
 3. The method according to claim 1 furthercharacterized by scanning each X-axis coordinate of the row of vialsbeing indexed along the Y-axis to determine the presence or absence of avial at each such X-axis coordinate and automatically indexing anyX-axis coordinate in said row devoid of a vial past said point alongsaid Y-axis coordinate.
 4. The method according to claim 1 furthercharacterized in that each vial positioned at said point is transferredfrom said point to a counting station and back to said point before thenext succeeding vial is indexed to said point.
 5. The method accordingto claim 4 further characterized in that the vial is transferred betweensaid point and said counting station along a Z-axis.
 6. A test samplechanging apparatus for use with at least one rectangular array of samplevials disposed in columns and rows along respective X and Y cartesiaNcoordinates of said array and for transferring all of said vials one ata time to a predetermined point, said apparatus comprising, an apparatusframe, means on said frame defining said point, a transfer station onsaid frame spaced from said point along a Y-axis coordinate, and meansfor holding at least one rectangular array of vials on said frame at alocation spaced from said station, characterized in that first indexingmeans are provided for incrementally indexing an entire one of saidarrays along the X-axis for sequentially aligning each Yoriented row ofvials with said station, second indexing means are provided for shiftingeach row of vials aligned with said transfer station along a Z-axis toshift said row of vials out of the plane of said array, third indexingmeans are provided for incrementally indexing each row of vials alignedwith said station along said Y-axis coordinate to sequentially positioneach vial contained in each said row at said predetermined point inseriatim order.
 7. Apparatus as set forth in claim 6 furthercharacterized in that said second indexing means is rendered operativeafter said first indexing means and prior to said third indexing means.8. Apparatus as set forth in claim 6 further characterized in that saidfirst, second and third indexing means are repetitively cycled in thefollowing order: a. said first means; b. said second means; c. saidthird means; d. said third means, reversely driven; and e. said secondmeans, reversely driven; until all of said vials in said rectangulararray have been transferred from said array to said point and back tosaid array.
 9. Apparatus as set forth in claim 6 further characterizedin that sensing means are provided for determining the presence of atleast one vial in each Y-oriented row of said array and for causing saidfirst indexing means to automatically index said array through multipleincrements so that Y-oriented rows devoid of vials are indexed past saidstation.
 10. Apparatus as set forth in claim 6 further characterized inthat sensing means are provided for determining the presence or absenceof a vial at each X-coordinate in the row of vials being indexed fromsaid station to said point and for causing said third indexing means toautomatically index said row through multiple increments so that eachX-coordinate in said row devoid of a vial is indexed past said point.11. Apparatus as set forth in claim 6 characterized in that means areprovided for transferring each vial positioned at said point from saidpoint to a sample processing station and back to said point. 12.Apparatus as set forth in claim 11 further characterized in that saidprocessing station comprises a light-tight chamber and means areprovided for counting light scintillations occurring in each said samplevial while the latter is positioned in said chamber.
 13. Apparatus asset forth in claim 11 further characterized in that said point and saidprocessing station are spaced apart on a Z-oriented axis.
 14. Apparatusset forth in claim 6 further characterized in that said third indexingmeans is operative only while said row of vials is out of the plane ofsaid array.